The present invention relates to a method of continuously producing resinoid abrasive wheels for cutting hard metal materials, especially superhard metal materials such as stainless steel and special steel.
Generally pores play an important role in resinoid abrasive wheels for cutting hard materials. When a hard metal material is cut by such a resinoid abrasive wheel, the pores in the wheel permit escape of particles of the cut material and reduce heat generation during the cutting operation. The presence of the pores further permits abrasion of the wheel, thereby refreshing the abrasive surface at all times so that the wheel retains a high cutting performance for a prolonged period of time. Accordingly such effects are not achievable if the amount of the pores is less than is desired, whereas the presence of an excessive amount of pores will reduce the strength of the wheel. Thus the amount of the pores is closely related to the cutting performance and strength of the abrasive wheel. It is therefore desired that a suitable amount of pores be present in the abrasive wheel in a well-balanced uniform distribution.
I have already proposed in U.S. Pat. No. 4,115,077 a method of continuously producing resinoid abrasive wheels containing pores uniformly distributed therein, comprising the steps of preparing pore forming granules having predetermined mechanical strength and containing a substance thermally decomposable at a baking temperature for the production of resinoid abrasive wheels, kneading the pore forming granules with abrasive grains, a binder, a glass fiber reinforcement and a filler to prepare an abrasive composition, molding the composition into a block, heating the block by a high frequency heater, rolling the block into a sheet by rolls, blanking out circular pieces from the sheet, and baking the circular pieces of the uncured abrasive composition containing the pore forming granules uniformly dispersed therein to cure the binder and form pores by the decomposition of at least part of the thermally decomposable substance in the granules. However, since the pore forming granules used in the proposed method contain only a thermally decomposable substance such as starch, the pores produced on baking are relatively small, so that the abrasive wheel obtained still remains to be improved in cutting performance.